A twin-spool turbojet comprises functionally, from upstream to downstream in the direction of flow of the gases, a fan in a casing, a compressor, a combustion chamber, a turbine and an exhaust nozzle. The two spools, low-pressure and high-pressure, rotate independently of one another and are coaxial. The turbojet comprises a low-pressure BP compressor, upstream of a high-pressure HP compressor, and an HP turbine, upstream of a BP turbine. “Internal” or “external”, or “inside” or “outside” will mean in the description radially internal or external to the engine, or radially inside or outside the engine, relative to its axis.
The fan comprises a fan disk, provided with blades, securely attached to the low-pressure shaft via a low-pressure rotor trunnion. Each fan blade extends radially in the engine and comprises, from outside to inside, an airfoil, a platform and a root arranged so as to engage in a groove of the fan disk.
When the blades rotate in the fan casing, the blades tend to vibrate which accelerates their wear and reduces their service life. In order to limit this wear, it is a known practice to place dampers under the platform of the blades in order to absorb the vibrations.
A damper is a rigid part which is placed under the platform, straddling two adjacent blades, so that, while the engine rotates, the damper presses against the platform.
Any relative movement between two adjacent blades causes a friction between the surfaces in contact with the blades and with the damper. This friction contributes to dissipating the energy of vibration.